Members of $99-a-Year Prime Club Can Stream Ultra HD Movies and TV Shows at No Additional Charge

Amazon is releasing a catalog of movies and television shows that stream in 4K, knocking down one of the chief reasons to hold out on buying the sharpest TV sets on the market.

Prices are falling on 4K—or “Ultra HD”—TVs that have four times the pixels of today’s high-definition models. The trouble has been finding the right content to go with them. Netflix was first with streaming 4K video, and Amazon on Tuesday made good on its pledge in November to introduce its own 4K catalog.